I am installing Exchange 2003 on my server. At the moment, all of my users have email from their ISP (@ISP.com). The domain name for their network (domain.com) is different than their ISP email address . I know how to set up Exchange to receive their ISP email (@ISP.com) and deliver it to their Exchange email account (@domain.com). My question is can I set up Exchange to send their email from their Exchange accoount (@domain.com) to their ISP account (@ISP.com), so that recipients outside of the network will see @ISP.com as the address rather than @domain.com?